A Manual of the Hand Lathe / Comprising Concise Directions for Working Metals of All Kinds, Ivory, Bone and Precious Woods

by Egbert P. Watson

Any one who has watched a novice at work on a lathe, must have remarked the difficulty he has in controlling the tool and keeping up the motion of the treadle at the same time. The two operations are difficult to “get the hang of,” to use a homely phrase; but once conquered, the work can proceed. The natural tendency is to slack up or stop the motion of the treadle while the tool is engaged, and the tool is, therefore, at one time under the work, at another time above it, at another jumping rankly in, until, finally, the piece goes whirling out of the center or the chuck, and the operator flushes all over at his awkwardness.

This, of course, is remedied by practice; and as this work is written mainly for the information of beginners and amateurs, we hope that experts and those who know all about hand lathes, will excuse allusion to such simple things as holding the tool properly, and kindred matters.

The lathe must be of such a height as the workman finds convenient, so that he is not obliged to stoop much, and, at the same time, low enough to allow the weight of the body to be thrown on the tool when hard work is to be done. The speed of the lathe ought to be very high on the smallest cone, and there should be three speeds, at least, for different work. The object is to regulate the velocity of the work in the lathe, and keep the motion of the treadle uniform, as near as may be, at all times. It distresses a workman greatly, when chasing a fine thread on a small diameter, if he has to tread fast to get up the proper speed, as he does when there are only two speeds. On the contrary, for larger jobs, it is difficult to keep up a rotary motion if the foot moves slowly, as it must in order not to burn the tool by a high velocity on some kinds of work. Foot lathes, in general, are not geared, although some are, and ought to have wider ranges of speed than they do. Where one class of work is done, however, it makes little difference, but for general turning, the speeds should vary.

Another difficulty experienced by beginners is in holding the tool still—rigidly so. They allow it to “bob” back and forth against the work, if it runs untrue, so that it is impossible to make a job. The tool must be held hard down, as if it grew to the rest, and never moved, nor receded, until the cut begun is finished.

The “rest” should be of soft, wrought iron, since that material holds a tool with more tenacity; imposing less strain on the arms of the operator. It should be dressed off smooth as often as it gets badly worn, or cut by indentations. Cast iron is not good, and steel is not so good as wrought iron. A special rest should be kept for chasing threads with, since the least obstacle is enough, when running up a fine thread, to divert the chaser and spoil the job, by making a drunken thread. If we now suppose the lathe to be in good order, the centers true and well-turned to a gauge, the rod (if that is the job) between them and properly “dogged,” the centers oiled, and the rest at the right height, we shall be all ready to start. The rest should be high enough to bring the point of the tool a little above the center.

Fig. 3.

To rough off the outside, and make it run true, is the first step, and the tool must, therefore, be held as in [Fig. 3], or so that the point and part of the edge alone engage with the work. This will take off a thin, spiral cut, without springing the shaft or making it untrue. The whole surface of the shaft must be thus run over, beginning at the right hand and shifting the tool as fast as one part is turned. The tool should not be moved rigidly in a straight line toward the belt, but by holding it hard down on the rest, so that the bottom edge bears as in [Fig. 2], and rocking the tool on that angle, so that the point describes a curve, as in [Fig. 4], the work will be turned evenly and true.

Fig. 4.